Signal processing device, method, and program

ABSTRACT

The present technology relates to a signal processing device, method, and program that may obtain audio at a higher audio quality when decoding an audio signal. 
     An envelope information generating unit  24  generates envelope information representing an envelope form of high frequency components of an audio signal to be encoded. A sine wave information generating unit  26  extracts a sine wave signal from the high frequency components of the audio signal, and generates a sine wave information representing an emergence start position of the sine wave signal. An encoding stream generating unit  27  multiplexes the envelope information, the sine wave information, and low frequency components of the audio signal that have been encoded, and outputs an encoding stream obtained as the result. As a result, the high frequency components included in the sine wave signal may be predicted at a higher accuracy from the envelope information and the sine wave information at the receiving side of the encoding stream. The present invention may be applied to a signal processing device.

TECHNICAL FIELD

The present invention relates to a signal processing device, method, andprogram, and particularly, relates to a signal processing device,program, and method that enables audio to be obtained at a higher audioquality in a case of decoding encoding audio signals.

BACKGROUND ART

In general, audio signal encoding methods such as HE-AAC (HighEfficiency MPEG (Moving Picture Experts Group) 4 AAC (Advanced AudioCoding)) (international standard ISO/IEC 14496-3) are known. With suchan encoding method, a high frequency feature encoding technology such asSBR (Spectral Band Replication) is used (for example, refer to PTL 1).

According to SBR, when encoding audio signals, SBR information is outputfor generating high frequency components of the audio signal (hereafter,referred to as high frequency signal) together with low frequencycomponents of the encoded audio signal (hereafter, low frequencysignal). At the decoding device, while decoding the encoded lowfrequency signal, the high frequency signal is generated by using thelow frequency signal obtained by the decoding and the SBR information,and so the audio signal made up of the low frequency signal and the highfrequency signal is obtained.

This kind of SBR information includes envelope information mainlyrepresenting an envelope form for the high frequency components, andnoise envelope information representing for obtaining a noise signaladded during the generation of the high frequency components at thedecoding device.

Here, the noise envelope information includes information representing aboundary position for dividing each SBR frame of the noise signalincluded in the high frequency components into two zones (hereafter,referred to as the noise boundary position), and informationrepresenting gain of noise signals in each zone. Therefore, at thedecoding device, a gain adjustment is performed on each zone divided bythe noise boundary position on a predetermined noise signal on the basisof the noise envelope information to establish a final noise signal.Further, with SBR, it is also possible to set the gain on the entire SBRframe without dividing the SBR frame of the noise signal into two zones.

When decoding the audio signal, the decoding device generates the highfrequency components by combining a pseudo high frequency signalobtained from the low frequency signal and the envelope information, andthe noise signal obtained from the noise envelope information, andgenerates the audio signal from the obtained high frequency componentsand the low frequency signal.

Also, with SBR, an encoding using sine wave synthesis is performed on anaudio signal with a high tone characteristic. That is to say, whengenerating the high frequency components at the decoding side, a sinewave signal of a particular frequency is added to the pseudo highfrequency signal in addition to the noise signal. In this case, thesignal obtained from combining the pseudo high frequency signal, thenoise signal, and the sine wave signal is set to the high frequencysignal obtained as a prediction.

When using a sine wave signal to predict the high frequency components,a sine wave information representing the existence/non-existence of thesine wave signal in the SBR frame is included in the SBR information.Specifically, the combination start position of the sine wave signalused during decoding is either the start position of the SBR frame orthe noise boundary position, and the sine wave information is made up ofbinary information representing the existence/non-existence of a sinewave signal combination in each zone of the SBR frame divided by thenoise boundary position.

In this way, the noise signal and the sine wave signal added to thepseudo high frequency signal are components that are difficult toreproduce from the envelope information within the high frequencycomponents of the source audio signal. Therefore, by combining the noisesignal and the sine wave signal at a suitable position in the pseudohigh frequency signal, it is possible to predict the high frequencycomponents with higher accuracy, and it is possible to reproduce audioat a higher audio quality by performing band pass expansion using thehigh frequency components obtained by prediction.

CITATION LIST Patent Literature

-   PTL 1: Japanese Unexamined Patent Application Publication    (Translation of PCT Application) No. 2001-521648

SUMMARY OF INVENTION Technical Problem

However, when using a sine wave signal to predict the high frequencycomponents, the combination start position of the sine wave signal isset as the SBR frame start position or the noise boundary position,which may cause variance in the emergence start position of the sinewave components in the original audio signal, in some cases. Thus, it isnot possible to reproduce the high frequency components with highaccuracy, and may cause degradation in the audible perception of theaudio signal obtained from the decoding.

Particularly with SBR, the frame length is fixed and not dependent onthe sampling rate of the audio signal to be encoded, and so when thesampling rate is low, the absolute time length for one frame becomeslonger. For this reason, the amount of variance (difference) in absolutetime between the emergence start position of the sine wave components inthe source audio signal and the combination start position of the sinewave signal to be combined during decoding increases, and quantizationnoise becomes noticeable at these zones of variance.

The present technology has been made taking this kind of situation intoconsideration to enable the obtainment of audio at a higher audioquality when decoding audio signals.

Solution to Problem

A signal processing device of a first aspect of the present invention isprovisioned with an extracting unit configured to extract an envelopeinformation representing low frequency components of an audio signal andan envelope of high frequency components of the audio signal and a sinewave information used for identifying the frequency and emergenceposition of sine wave components included in the high frequencycomponents, a pseudo high frequency generating unit configured togenerate a pseudo high frequency signal configuring the high frequencycomponents on the basis of the low frequency signal as the low frequencycomponent and the envelope information, a sine wave generating unitconfigured to generate a sine wave signal at a frequency represented bythe sine wave information and which designates the emergence positionidentified from the sine wave information as the start position, and acombining unit configured to combine the low frequency signal, thepseudo high frequency signal, and the sine wave signal to generate theaudio signal.

The sine wave information may include information representing thedistance from the start position of a frame of the high frequencycomponent until the emergence start position of the sine wave componentas information used for identifying the emergence position.

The signal processing device is further provisioned with a noisegenerating unit configured to generate a noise signal configuring thehigh frequency components by adjusting the gain of each zone of apredetermined signal, in which the zones are divided by a noise boundaryposition represented by a noise envelope information, on the basis ofinformation representing the gain of each zone represented by the noiseenvelope information, wherein the extracting unit further extracts thenoise envelope information, the sine wave information includesinformation representing the distance from the noise boundary positionuntil the emergence start position of the sine wave components as theinformation used for identifying the emergence position, and thecombining unit may combines the low frequency signal, the pseudo highfrequency signal, the sine wave signal, and the noise signal to generatethe audio signal.

The sine wave information may include information representing thedistance from a peak position of the high frequency component envelopeuntil the emergence start position of the sine wave component as theinformation used for identifying the emergence position.

The sine wave information may be extracted for each frame, and the sinewave generating unit may generate the sine wave signal for the highfrequency components of each frame.

The sine wave information may be extracted for each band configuring thehigh frequency components, and the sine wave generating unit maygenerate the sine wave signal for each band.

A signal processing method or program of the first aspect of the presentinvention includes the steps of extracting the low frequency componentsof the audio signal, the envelope information representing the envelopeof the high frequency component of the audio signal, and the sine waveinformation used for identifying the frequency and emergence startposition of the sine wave component included in the high frequencycomponents, generating the pseudo high frequency signal configuring thehigh frequency components on the basis of a low frequency signal as thelow frequency component and the envelope information, generating a sinewave signal at the frequency represented by the sine wave information ata start position identified by the emergence start position from thesine wave information, and combining the low frequency signal, thepseudo high frequency signal, and the sine wave signal to generate theaudio signal.

Regarding the first aspect of the present invention, the envelopeinformation representing low frequency components of an audio signal andan envelope of high frequency components of the audio signal and sinewave information used for identifying the frequency and emergenceposition of sine wave components included in the high frequencycomponents are extracted, a pseudo high frequency signal configuring thehigh frequency components is generated on the basis of the low frequencysignal as the low frequency component and the envelope information, asine wave signal at a frequency represented by the sine wave informationand which designates the emergence position identified from the sinewave information as the start position is generated, and the lowfrequency signal, the pseudo high frequency signal, and the sine wavesignal are combined to generate the audio signal.

A signal processing device of a second aspect of the present inventionis provisioned with an envelope information generating unit configuredto generate envelope information representing an envelope of a highfrequency signal, which is the high frequency component of an audiosignal, a sine wave information generating unit configured to detect asine wave signal included in the high frequency signal, and generating asine wave information used for identifying the frequency and emergenceposition of the sine wave signal, and an output unit configured togenerate and output data made up from a low frequency signal, which is alow frequency component of the audio signal, the envelope information,and the sine wave information.

The sine wave information may include information representing thedistance from the start position of a frame of the high frequencycomponent until the emergence start position of the sine wave signal asinformation used for identifying the emergence position.

The signal processing device is further provisioned with a noiseenvelope information generating unit configured to detect a noise signalincluded in the high frequency signal, and generating a noise envelopeinformation made up from information representing a noise boundaryposition which divides the noise signal into multiple zones andinformation representing the gain of the noise signal in the zone,wherein the sine wave information includes information representing thedistance from the noise boundary position until the emergence startposition of the sine wave components as the information used foridentifying the emergence position, and the output unit may generate andoutput data made up from the low frequency signal, the envelopeinformation, the sine wave information, and the noise envelopeinformation.

The sine wave information may include information representing thedistance from a peak position of the high frequency component envelopeuntil the emergence start position of the sine wave component as theinformation used for identifying the emergence position.

The sine wave information may be generated for each frame.

The sine wave information may be generated for each band configuring thehigh frequency components.

A signal processing method or program of the second aspect of thepresent invention includes the steps of generating envelope informationrepresenting an envelope of a high frequency signal, which is the highfrequency component of an audio signal, generating sine wave informationincluded in the high frequency signal is detected, and a sine waveinformation used for identifying the frequency and emergence position ofthe sine wave signal, and generating and outputting data made up from alow frequency signal, which is the low frequency component of the audiosignal, the envelope information, and the sine wave information.

Regarding the second aspect of the present invention, envelopeinformation representing an envelope of a high frequency signal, whichis a high frequency component of an audio signal, is generated, a sinewave signal included in the high frequency signal is detected, and asine wave information used for identifying the frequency and emergenceposition of the sine wave signal is generated, and data made up from alow frequency signal, which is a low frequency component of the audiosignal, the envelope information, and the sine wave information isgenerated and output.

Advantageous Effects of Invention

According to the first aspect and the second aspect of the presenttechnology, audio may be obtained at a higher audio quality whendecoding an audio signal.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a configuration example of a firstEmbodiment of an encoding device.

FIG. 2 is a flowchart describing an encoding processing.

FIG. 3 is a diagram illustrating a combination start position of a sinewave signal.

FIG. 4 is a diagram illustrating a combination start position of a sinewave signal.

FIG. 5 is a diagram illustrating a configuration example of the firstEmbodiment of a decoding device.

FIG. 6 is a flowchart describing a decoding processing.

FIG. 7 is a flowchart describing a processing to generate the sine wavesignal.

FIG. 8 is a diagram illustrating a configuration example of anotherencoding device.

FIG. 9 is a flowchart describing an encoding processing.

FIG. 10 is a diagram describing a combination start position of the sinewave signal.

FIG. 11 is a diagram illustrating a configuration example of anotherdecoding device.

FIG. 12 is a flowchart describing a decoding processing.

FIG. 13 is a flowchart describing a processing to generate the sine wavesignal.

FIG. 14 is a diagram illustrating a configuration example of anotherencoding device.

FIG. 15 is a flowchart describing an encoding processing.

FIG. 16 is a diagram describing a combination start position of the sinewave signal.

FIG. 17 is a diagram illustrating a configuration example of anotherdecoding device.

FIG. 18 is a flowchart describing a decoding processing.

FIG. 19 is a flowchart describing a processing to generate the sine wavesignal.

FIG. 20 is a diagram illustrating a configuration example of anotherencoding device.

FIG. 21 is a flowchart describing an encoding processing.

FIG. 22 is a diagram illustrating a configuration example of anotherdecoding device.

FIG. 23 is a flowchart describing a decoding processing.

FIG. 24 is a flowchart describing a processing to generate the sine wavesignal.

FIG. 25 is a diagram illustrating a configuration example of a computer.

DESCRIPTION OF EMBODIMENTS

Hereafter, the embodiments applying the present technology will bedescribed with reference to the drawings.

First Embodiment [Configuration Example of Encoding Device]

FIG. 1 is a diagram illustrating a configuration example of a firstEmbodiment of an encoding device applying the present technology.

An encoding device 11 is configured with a downsampler 21, a lowfrequency encoding unit 22, a band pass division filter 23, an envelopeinformation generating unit 24, a noise envelope information generatingunit 25, a sine wave information generating unit 26, and an encodingstream generating unit 27. The encoding device 11 encodes and outputs aninput audio signal, and the audio signal input into the encoding device11 is supplied to the downsampler 21 and the band pass division filter23.

The downsampler 21 extracts the low frequency signal, which is the lowfrequency components of the audio signal, by downsampling the inputaudio signal, and supplies this to the low frequency encoding unit 22and the noise envelope information generating unit 25. Further,hereafter, the frequency band components at or below a certain frequencyof the audio signal are referred to as the low frequency components, andthe frequency band components higher than the low frequency componentsof the audio signal are referred to as the high frequency components.

The low frequency encoding unit 22 encodes the low frequency signalsupplied from the downsampler 21, and supplies this to the encodingstream generating unit 27.

The band pass division filter 23 conducts a filter processing on theinput audio signal, and performs a band pass division of the audiosignal. As a result of this band pass division, the audio signal isdivided into a signal of multiple band components. Further, hereafter,each band signal configuring the high frequency components from withineach band signal obtained by the band pass division is referred to asthe high frequency signal. The band pass division filter 23 supplies thehigh frequency signal from the high frequency side of each band obtainedby the band pass division to the envelope information generating unit24, the noise envelope information generating unit 25, and the sine waveinformation generating unit 26.

The envelope information generating unit 24 generates an envelopeinformation representing a form of an envelope (envelope) for the highfrequency signal of the band for each band on the high frequency side onthe basis of the high frequency signal supplied from the band passdivision filter 23, and then supplies this to the noise envelopeinformation generating unit 25. Also, the envelope informationgenerating unit 24 is provisioned with an encoding unit 41, and theencoding unit 41 encodes the envelope information generated by theenvelope information generating unit 24, and supplies this to theencoding stream generating unit 27.

The noise envelope information generating unit 25 generates a noiseenvelope information while receiving information from the sine waveinformation generating unit 26 as necessary, on the basis of the highfrequency signal from the band pass division filter 23 and the envelopeinformation from the envelope information generating unit 24.

Here, the noise envelope information is information made up frominformation representing a boundary position (noise boundary position)for dividing the noise signal included in the high frequency componentsof the audio signal, and information representing the noise signal gainfor each zone divided at the noise boundary position. Further, the noisesignal is a previously determined signal.

Also, the noise envelope information generating unit 25 is provisionedwith a signal generating unit 51, a boundary calculating unit 52, and anencoding unit 53. When generating noise envelope information, the signalgenerating unit 51 predicts the high frequency side of the audio signalfor each band component on the basis of the low frequency signal fromthe downsampler 21 and the envelope information from the envelopeinformation generating unit 24.

The boundary calculating unit 52 determines the noise boundary positionused for dividing the noise signal into multiple zones on the basis ofthe noise signal envelope obtained from the high frequency signal and apseudo high frequency signal, which is the result of the high frequencyside of each band pass component predicted during the generation of thenoise envelope information. The encoding unit 53 encodes the noiseenvelope information generated by the noise envelope informationgenerating unit 25, and supplies this to the encoding stream generatingunit 27.

The sine wave information generating unit 26 generates sine waveinformation used for obtaining the sine wave signal included in the bandfor each band at the high frequency side while receiving the informationfrom the noise envelope information generating unit 25 as necessary, onthe basis of the high frequency signal supplied from the band passdivision filter 23.

Here, the sine wave information is information made up from informationrepresenting the existence/non-existence of a sine wave signal includedin the high frequency components of the audio signal, and informationused for identifying the emergence start position of the sine wavesignal. That is to say, the sine wave information may be informationmade up from information representing the existence/non-existence of asine wave signal to be combined with the pseudo high frequencycomponents during decoding of the audio signal, and informationrepresenting the combination start position of the sine wave signal.

Also, then sine wave information generating unit 26 is provisioned witha sine wave detection unit 61, a position detection unit 62, and anencoding unit 63. The sine wave detection unit 61 detects theexistence/non-existence of the sine wave components from the highfrequency signal during generation of the sine wave information.

When generating sine wave information, the position detection unit 62detects the combination start position indicating where the combinationof the sine wave signal should start, that is to say, the emergencestart position of the sine wave signal, on the basis of the highfrequency signal from the band pass division filter 23. The encodingunit 63 encodes the sine wave information generated by the sine waveinformation generating unit 26, and supplies this to the encoding streamgenerating unit 27.

The encoding stream generating unit 27 encodes the low frequency signalfrom the low frequency encoding unit 22, the envelope information fromthe envelope information generating unit 24, the noise envelopeinformation from the noise envelope information generating unit 25, andthe sine wave information from the sine wave information generating unit26, and outputs the encoding stream obtained from this encoding. That isto say, the low frequency signal, the envelope information, the noiseenvelope information, and the sine wave information are multiplexed intothe encoding stream.

[Description of Encoding Processing]

Next, the operation of the encoding device 11 will be described.

When the audio signal is input into the encoding device 11, andinstructed to encode the audio signal, the encoding device 11 performsthe encoding processing to perform the encoding of the audio signal, andoutputs the encoding stream obtained as the result. Hereafter, theencoding processing by the encoding device 11 will be described withreference to the flowchart in FIG. 2.

At a step S11, the downsampler 21 downsamples the input audio signal togenerate the low frequency signal, and supplies this to the noiseenvelope information generating unit 25 and the low frequency encodingunit 22.

At a step S12, the low frequency encoding unit 22 encodes the lowfrequency signal supplied from the downsampler 21, and supplies this tothe encoding stream generating unit 27. For example, the low frequencysignal is encoded by an encoding method such as MPEG4 AAC, MPEG2 AAC,CELP (Code Exited Linear Prediction), TCX (Transform Coded Excitation),or AMR (Adaptive Multi-Rate).

At a step S13, the band pass division filter 23 divides the input audiosignal into bands, and the high frequency components obtained as theresult are supplied to the envelope information generating unit 24through the sine wave information generating unit 26. For example, highfrequency signals may be obtained as high frequency components from 64different bands.

At a step S14, the envelope information generating unit 24 generates theenvelope information for each band on the basis of the high frequencysignal for each band supplied from the band pass division filter 23. Forexample, the envelope information generating unit 24 may designate azone made up of 32 samples of the high frequency signal as one frame,and generate the envelope information for each band per frame.

Specifically, the envelope information generating unit 24 obtains anaverage sample value of two samples of the high frequency signalneighboring on a time line in one frame, and this average value becomesthe new high frequency signal sample value. As a result, the highfrequency signal for one frame is converted from a 32-sample signal to a16-sample signal.

Next, the envelope information generating unit 24 performs a differenceencoding on the high frequency signal that is now 16 samples, and theinformation obtained as the result becomes the envelope information. Forexample, the difference between the sample value of two high frequencysignal samples to be processed neighboring on a time line is obtained bythe difference encoding, and this difference becomes the envelopeinformation. Also, the envelope information may be made up of thedifference between the sample value of a sample of the high frequencysignal of the band to be processed and the sample value of a sample in aband adjacent to that band, in the same position as the high frequencysignal band, for example.

The envelope information obtained in this way is the informationrepresenting the form of the envelope for one frame of the highfrequency signal. The encoding unit 41 performs a variable lengthencoding such as Huffman encoding on the generated envelope information,and supplies the encoded envelope information to the encoding streamgenerating unit 27. Also, the envelope information generating unit 24supplies the envelope information to the noise envelope informationgenerating unit 25.

Further, hereafter, the high frequency signal will continue to bedescribed as that processed in units of one frame configured of 32samples. Also, hereafter, the zone configured from two samples of thehigh frequency signal (audio signal) will be called one timeslot.

At a step S15, the signal generating unit 51 in the noise envelopeinformation generating unit 25 generates the pseudo high frequencysignal for each band at the high frequency side on the basis of theenvelope information supplied from the envelope information generatingunit 24 and the low frequency signal supplied from the downsampler 21.

For example, the signal generating unit 51 extracts the zone for oneframe of a predetermined band of the low frequency signal, andmanipulates the extracted low frequency signal into the envelope formrepresented by the envelope information. That is to say, the samplevalue of the sample of the low frequency signal is increased ordecreased so that the position gain corresponding to the sample fits inthe envelope represented by the envelope information, and the signalobtained as the result becomes the pseudo high frequency signal.

The pseudo high frequency signal obtained in this way has the almost thesame envelope form as the envelope of the actual high frequency signalrepresented by the envelope information. That is to say, the pseudo highfrequency signal is generated from the low frequency signal and theenvelope information.

At a step S16, the noise envelope information generating unit 25extracts the difference between the high frequency signal and the pseudohigh frequency signal for each band at the high frequency side, andobtains the envelope for the noise signal (hereafter, referred to as thenoise envelope).

Further, more specifically, the noise envelope obtained at step S16 is avirtual noise envelope. The receiving side of the encoding stream outputfrom the encoding device 11 predicts the high frequency components ofthe audio signal during the decoding of the audio signal, but thisprediction is performed by combining of the pseudo high frequencysignal, the noise signal, and the sine wave signal.

That is to say, the high frequency components of the actual audio signalare assumed to include the pseudo high frequency signal, the noisesignal, and the sine wave signal. Here, at the step S16, the differencebetween the high frequency signal and the pseudo high frequency signalis obtained, and this difference should be the combination of the noisesignal and the sine wave signal. Thus, the difference obtained in thisway is considered as the envelope of the noise signal including the sinewave signal.

The noise envelope information generating unit 25 supplies the virtualnoise envelope for each band at the high frequency side obtained aspreviously described to the sine wave information generating unit 26.

At a step S17, the sine wave detection unit 61 in the sine waveinformation generating unit 26 detects the sine wave components from thehigh frequency signal for each band on the basis of the virtual noiseenvelope supplied from the noise envelope information generating unit25.

For example, the sine wave detection unit 61 conducts a frequencyconversion on the virtual noise envelope, and converts the noiseenvelope into frequency components. Then, when there are frequencyspikes having high power in the obtained frequency components, the sinewave detection unit 61 recognizes these frequency components as the sinewave components. Specifically, when the difference between the power ofthe frequency under observation and the power of other surroundingfrequencies is at or above a predetermined threshold, the frequencyunder observation is recognized as the sine wave component. The sinewave signal for the frequency detected in this way is determined as thesine wave signal included in the actual high frequency components.

At a step S18, the position detection unit 62 in the sine waveinformation generating unit 26 detects, for each band, the combinationstart position where the sine wave signal, which is the detected sinewave component, should be combined on the basis of the high frequencysignal supplied from the band pass division filter 23.

For example, the position detection unit 62 obtains the differencebetween the average sample value of the samples included in one timeslotof the high frequency signal, in units of timeslots, and the averagesample value of samples included in one timeslot of the detected sinewave signal. Then, the position detection unit 62 determines thecombination start position looking from the beginning of the zone forone frame as the final position (start position of the timeslot or thefinal position of the sample) where the value of the obtained differenceis at or above a predetermined threshold. This combination startposition is the emergence start position of the sine wave signalincluded in the actual high frequency signals, from a timing after thecombination start position, the difference in the average sample valuesof the high frequency signal and the sine wave signal should decrease.

Also, for each band at the high frequency side, the sine waveinformation generating unit 26 supplies the information representingwhether or not the sine wave has been detected from the bands, theinformation representing the frequency and power of the detected sinewave signal, and the combination start position to the noise envelopeinformation generating unit 25.

At a step S19, the sine wave information generating unit 26 generatesthe sine wave information for each band at the high frequency side, andsupplies this to the encoding stream generating unit 27.

For example, the sine wave information generating unit 26 designates theinformation made up from the information representing whether or not thesine wave signal has been detected from the high frequency band and thecombination start position as the sine wave information. Also, duringthe generation of the sine wave information, the encoding unit 63 in thesine wave information generating unit 26 performs the variable lengthencoding of the information representing the combination start position.

Here, the information representing whether or not the sine wave signalhas been detected is, more specifically, information representing whichfrequency in the high frequency band is the sine wave component. Forexample, when multiple sine wave signals are detected from the highfrequency band, the information used for identifying the frequencies ofthese sine wave signals is designated as the information representingwhether or not the sine wave signals were detected. Also, when multiplesine wave signals are detected from the high frequency band, informationrepresenting the combination start position is generated for each sinewave signal.

Also, when the sine wave component is not detected from the highfrequency band, the sine wave information made up only of informationrepresenting whether or not the sine wave signal has been detected istransmitted to the decoding side. That is to say, the sine waveinformation not including information representing the combination startposition is transmitted.

Further, the encoding device 11 may select whether or not to transmitthe sine wave information to the decoding side per frame. In this way,by enabling the transmission of the sine wave information to beselectable, transfer efficiency of the encoding stream in increased, andat the same time, a resetting of the time information of the sine wavecomponents may be performed. As a result, when starting the decodingprocessing from an arbitrary frame within the stream on the decodingside of the encoding stream, the sine wave component from the frameincluding the information representing the combination start positionmay be started.

Further, as illustrated in FIG. 3 for example, the combination startposition on the decoding side has conventionally been either the startposition of the frame or the noise boundary position. Further, thehorizontal axis in the figure represents the time line. Also, an arrowFS1 and an arrow FE1 in FIG. 3 represent the start position and endposition of the frame, respectively.

According to the example in FIG. 3, the position represented by an arrowN1 is the noise boundary position, and the combination start position ofthe sine wave signal is also in the same position as the noise boundaryposition. Therefore, the sine wave signal is combined in a zone from theposition represented by the arrow N1 until the end position of theframe.

However, when the position that sine wave signal included in the actualhigh frequency components arrives is after the noise boundary positionrepresented by the arrow N1, for example, at the decoding side,unnecessary sine wave components are added in the space from the noiseboundary position to the emergence start position of the actual sinewave signal. In this case, there is an unpleasant audible sensation inthe audio signal obtained by the decoding, and audio at a high audioquality is unable to be obtained.

Regarding this, as illustrated in FIG. 4, according to the encodingdevice 11, the combination start position output to the decoding side isnot limited to being the same as the noise boundary position. Further,the horizontal axis in the figure represents the time line. Also, anarrow FS2 and arrow FE2 in FIG. 4 represent the start position and theend position of the frame, respectively.

According to the example in FIG. 4, the position represented by an arrowN2 represents the noise boundary position. Also, the combination startposition of the sine wave signal is the position represented by an arrowG1, and this combination start position is before the noise boundaryposition. According to this example, the sine wave signal is combined inthe zone from the combination start position represented by the arrow G1until the end position of the frame.

Also, in this case, the information representing the length of time(time distance) from the start position of the frame represented by thearrow FS2 until the combination start position represented by the arrowG1 is designated as the information representing the combination startposition. Here, the time from the beginning of the frame until thecombination start position is an integral multiple of the timeslotlength.

In this way, by specifying the combination start position independent ofthe noise boundary position, the combination of unnecessary signals isprevented during the decoding of the audio signal, and audio at a higheraudio quality may be obtained.

Further, the sine wave information has been previously described asinformation generated representing the combination start position forthe high frequency side for each band, but the sine wave information mayuse a representative value of the combination start positions for thesebands shared for each band configuring the high frequency. In such acase, for example, the information representing the combination startposition for the band out of multiple bands configuring the highfrequency which has the sine wave signal of the highest power becomesthe sine wave information.

Also, the information representing the combination start position hasbeen described above as the sine wave information to which variablelength encoding has been performed, but the information representing thecombination start position may not be encoded.

Returning to the description of the flowchart in FIG. 2, at the stepS19, the sine wave information is generated, and afterwards, processingproceeds to a step S20.

At a step S20, the boundary calculating unit 52 in the noise envelopeinformation generating unit 25 detects the noise boundary position foreach band at the high frequency side.

For example, the boundary calculating unit 52 generates the sine waveinformation included in the frame for the band configuring the highfrequency on the basis of the information representing whether or notthe sine wave signal has been detected, the information representing thefrequency and power of the sine wave signal, and the combination startposition. For example, when the sine wave signal is detected, the zonefrom the beginning of the frame until the combination start position isdesignated as a silent zone, and the zone from this point is made up ofthe sine wave component of a predetermined amplitude of the detectedfrequency. At this time, the amplitude of the sine wave signal isdetermined from the information representing the power of the sine wavesignal supplied from the sine wave information generating unit 26. Also,when the sine wave signal is not detected, the amplitude of the sinewave signal is set to zero.

Next, the boundary calculating unit 52 subtracts the sine wave signalobtained in this way from the virtual noise envelope obtained at a stepS16 to obtain the final noise envelope. Then, the boundary calculatingunit 52 determines the noise boundary position according to thedistribution of the final noise envelope gain.

That is to say, the boundary calculating unit 52 divides the frame intotwo zones as necessary based on the distribution of the gain of thefinal noise envelope. Specifically, when the noise envelope gain isnearly the same value for the entire frame of the band being processed,the division of the frame is not performed. That is to say, there is nonoise boundary position.

Also, when there is a large difference in the gain distribution of thenoise envelope at a predetermined position in the frame for the zonebefore this position and the zone after this position, this positionbecomes the noise boundary position. Further, the noise boundaryposition is designated as the timeslot boundary position.

At a step S21, the noise envelope information generating unit 25generates the noise envelope information for each band at the highfrequency side, and supplies this to the encoding stream generating unit27.

For example, the noise envelope information generating unit 25designates the noise envelope information as the information made upfrom the noise boundary position, and the noise signal gain in each zonein the frame divided by this noise boundary position. At this time, theencoding unit 53 performs an encoding of the information representingthe noise boundary position, and a variable length encoding of theinformation representing the gain for each divided zone.

Here, the gain for each divided zone is the average gain value of thenoise envelope in these zones, for example. That is to say, the framebeing processed is divided into two zones by the noise boundaryposition. In this case, the gain for the zone from the beginning of theframe until the noise boundary position is the average gain value foreach position of the final noise envelope in this zone.

At a step S22, the encoding stream generating unit 27 encodes the lowfrequency signal from the low frequency encoding unit 22, the envelopeinformation from the envelope information generating unit 24, the noiseenvelope information from the noise envelope information generating unit25, and the sine wave information from the sine wave informationgenerating unit 26, and generates the encoding stream. Then, theencoding stream generating unit 27 transmits the encoding streamobtained from the encoding to the decoding device, etc., and theencoding processing terminates.

In this way, the encoding device 11 generates and outputs the encodingstream made up from the low frequency signal, the envelope information,the noise envelope information, and the sine wave information. At thistime, by a more accurate combination start position of the sine wavesignal being detected, and generating the sine wave informationincluding this combination start position, a more accurate sine wavesignal combination may be performed at the decoding side of the audiosignal, which results in the obtainment of audio at a higher audioquality.

Further, the low frequency signal generated by the downsampler 21 hasbeen described above to be supplied to the noise envelope informationgenerating unit 25, but the low frequency signal supplied to the noiseenvelope information generating unit 25 may be a low frequency signalobtained by division of the bands by the band pass division filter 23.Also, the low frequency signal encoded by the low frequency encodingunit 22 is obtained by decoding, but this may also be supplied to thenoise envelope information generating unit 25.

[Configuration Example of Decoding Device]

Next, a decoding device which receives the encoding stream output fromthe encoding device 11 in FIG. 1, and obtains the audio signal from theencoding stream will be described. This kind of decoding device isconfigured as illustrated in FIG. 5, for example.

A decoding device 91 in FIG. 5 is configured with an encoding streamdecoding unit 101, a low frequency decoding unit 102, an envelopeinformation decoding unit 103, a noise envelope information decodingunit 104, a sine wave information decoding unit 105, and a band passcombination filter 106.

The encoding stream decoding unit 101 receives and decodes the encodingstream transmitted from the encoding device 11. That is to say, theencoding stream decoding unit 101 inverse multiplexes the encodingstream, and the low frequency signal, the envelope information, thenoise envelope information, and the sine wave information obtained as aresult is supplied to the low frequency decoding unit 102, the envelopeinformation decoding unit 103, the noise envelope information decodingunit 104, and the sine wave information decoding unit 105, respectively.

The low frequency decoding unit 102 decodes the low frequency signalsupplied from the encoding stream decoding unit 101, and supplies thisto the envelope information decoding unit 103 and the band passcombination filter 106.

The envelope information decoding unit 103 decodes the envelopeinformation supplied from the encoding stream decoding unit 101, andalso supplies the decoded envelope information to the sine waveinformation decoding unit 105. Also, the envelope information decodingunit 103 is provisioned with a generating unit 121, and the generatingunit 121 generates envelop information and the pseudo high frequencysignal based on the low frequency signal from the low frequency decodingunit 102, and supplies this to the band pass combination filter 106.

The noise envelope information decoding unit 104 decodes the noiseenvelope information supplied from the encoding stream decoding unit101. Also, the noise envelope information decoding unit 104 isprovisioned with a generating unit 131, and the generating unit 131generates the noise signal based on the noise envelope information, andsupplies this to the band pass combination filter 106.

The sine wave information decoding unit 105 decodes the sine waveinformation supplied from the encoding stream decoding unit 101. Also,the sine wave information decoding unit 105 is provisioned with agenerating unit 141, and the generating unit 141 generates the sine wavesignal based on the sine wave information and envelope information fromthe envelope information decoding unit 103, and supplies this to theband pass combination filter 106.

The band pass combination filter 106 combines the bands of the lowfrequency signal from the low frequency decoding unit 102, the pseudohigh frequency signal from the envelope information decoding unit 103,the noise signal from the noise envelope information decoding unit 104,and the sine wave signal from the sine wave information decoding unit105 to generate the audio signal. The band pass combination filter 106outputs the signal obtained from combining the bands as the decodedaudio signal to a downstream player unit or similar.

[Description of Decoding Processing]

When the encoding stream from the encoding device 11 is transmitted tothe decoding device 91 illustrated in FIG. 5, the decoding device 91performs the decoding processing in units of frames to decode the audiosignal. Hereafter, the decoding processing performed by the decodingdevice 91 will be described with reference to FIG. 6.

At a step S1, the encoding stream decoding unit 101 decodes the encodingstream received from the encoding device 11, and supplies the lowfrequency signal, envelope information, noise envelope information, andsine wave information obtained as a result to the low frequency decodingunit 102 through the sine wave information decoding unit 105.

At a step S52, the low frequency decoding unit 102 decoded the lowfrequency signal from the encoding stream decoding unit 101, andsupplies this to the envelope information decoding unit 103 and the bandpass combination filter 106.

At a step S53, the envelope information decoding unit 103 decodes theenvelope information from the encoding stream decoding unit 101. Also,the envelope information decoding unit 103 supplies the decoded envelopeinformation to the sine wave information decoding unit 105.

At a step S54, the generating unit 121 in the envelope informationdecoding unit 103 generates the pseudo high frequency signal for eachband at the high frequency side, on the basis of the low frequencysignal from the low frequency decoding unit 102, and supplies this tothe band pass combination filter 106. For example, the generating unit121 generates the pseudo high frequency signal by extracting the zonefor one frame regarding a predetermined band of the low frequencysignal, and increasing or decreasing the low frequency signal so thatthe sample value of the extracted low frequency signal sample matchesthe gain of the position in the envelope represented by the envelopeinformation corresponding to this sample.

At a step S55, the noise envelope information decoding unit 104 decodesthe noise envelope information from the encoding stream decoding unit101.

At a step S56, the generating unit 131 in the noise envelope informationdecoding unit 104 generates the noise signal for each band at the highfrequency side, on the basis of the noise envelope information, andsupplies this to the band pass combination filter 106. That is to say,the generating unit 131 generates the noise signal by adjusting the gainfor each zone of a predetermined signal which has been divided intozones by the noise boundary position represented by the noise envelopeinformation so that the gain of this signal matches the gain representedby the noise envelope information.

At a step S57, the sine wave information decoding unit 105 decodes thesine wave information from the encoding stream decoding unit 101. Forexample, the information representing the combination start positionincluded in the sine wave information is decoded as necessary.

At a step S58, the sine wave information decoding unit 105 performs thesine wave signal generation processing to generate the sine wave signalfor each band at the high frequency side, and supplies this to the bandpass combination filter 106. Further, the details of the sine wavesignal generation processing will be described later.

At a step S59, the band pass combination filter 106 combines the bandsof the low frequency signal from the low frequency decoding unit 102,the pseudo high frequency signal from the envelope information decodingunit 103, the noise signal from the noise envelope information decodingunit 104, and the sine wave signal from the sine wave informationdecoding unit 105.

That is to say, the audio signal is generated by performing the bandcombination by adding the samples at each timing from the low frequencysignal, the pseudo high frequency signal for each band, the noise signalfor each band, and the sine wave signal for each band input from the lowfrequency decoding unit 102 through the sine wave information decodingunit 105. Here, the signal made up of the pseudo high frequency signal,the noise signal, and the sine wave signal is the high frequencycomponent obtained by prediction.

When the audio signal has been obtained by the band combination, theband pass combination filter 106 outputs this audio signal to adownstream player unit or similar, and the decoding processingterminates. This decoding processing is performed per frame, and as thenext frame of the encoding stream is input, the decoding device 91performs the decoding processing on this frame of the encoding stream.

In this way, the decoding device 91 predicts the high frequencycomponents on the basis of the low frequency signal, the envelopeinformation, the noise envelope information, and the sine waveinformation, and generates the audio signal by expanding the bands fromthe high frequency signal obtained by prediction and the decoded lowfrequency signal. At this time, by using the sine wave informationrepresenting a more accurate combination start position of the sine wavesignal, a more accurate sine wave signal combination may be performed,and so audio at a higher audio quality may be obtained.

[Description of the Sine Wave Signal Generation Processing]

Next, the sine wave signal generation processing corresponding to stepS58 of the processing in FIG. 6 will be described with reference to theflowchart in FIG. 7.

At a step S81, the generating unit 141 in the sine wave informationdecoding unit 105 determines whether or not the start timing for thesine wave signal combination processing has passed based on thecombination start position and the information included in the sine waveinformation representing whether or not the sine wave signal has beendetected.

For example, the generating unit 141 generates the sine wave signal asthe sine wave component configuring the high frequency component bydesignating the beginning of the frame as the emergence start positionand the end of the frame as the emergence end position.

Here, the frequency of the sine wave signal designated as the sine wavecomponent configuring the high frequency component is identified by theinformation included in the sine wave information representing whetheror not the sine wave signal has been detected. Also, the amplitude ofthe sine wave signal frequency identified by the sine wave informationis identified from the envelope information supplied from the envelopeinformation decoding unit 103 through the sine wave information decodingunit 105. For example, the generating unit 141 converts the envelopeinformation into frequencies, and obtains the amplitude of the sine wavesignal based on the power of the sine wave signal frequency from amongthe power of all frequencies obtained as a result.

Next, the generating unit 141 selects the sample in the start positionof the timeslot for one frame of the sine wave signal as the sample(timeslot) to be processed in order from the beginning of the frame.Then, the generating unit 141 determines whether or not the selectedsample position is the sample position represented by the combinationstart position, that is to say the timing at which the combination ofthe sine wave signal should be started. For example, when informationincluded in the sine wave information indicates that the sine wavesignal has not been detected, this will continue to be determined thatthe start timing of the sine wave combination processing has not passed.

When it has been determined that the start timing has not passed at thestep S81, at a step S82, the generating unit 141 shifts the generatedsine wave signal backward on a timeline by one timeslot. As a result,the emergence start position of the sine wave signal is shifted backwardon a timeline. When the shifting of the sine wave signal is performed,the sine wave has not yet emerged in the timeslot zone to be processed,and so the sine wave signal is not output from the sine wave informationdecoding unit 105 to the band pass combination filter 106.

At a step S83, the generating unit 141 determines whether or not the endof one frame has been reached. For example, when the zone for the finaltimeslot configuring the frame is being processed, that is to say, whenall timeslots in the frame have been processed, this is determined thatthe end of the frame has been reached.

When it has been determined that the end of the frame has not beenreached at the step S83, the next timeslot is selected as that to beprocessed, the processing returns to step S81, and the previouslydescribed processing repeats. In this case, the shit processing, etc. isperformed on the sine wave signal already generated.

Conversely, when it has been determined that the end of the frame hasbeen reached at the step S83, the sine wave signal generation processingterminates, and afterwards, the processing proceeds to a step S59 inFIG. 6. In this case, the result is that the sine wave signalcombination is not performed.

Also, when it has been determined that the start position of the sinewave combination processing has passed at the step S81, at a step S84,the generating unit 141 performs the sine wave combination processing.That is to say, the generating unit 141 outputs to the band passcombination filter 106 the sample value configuring the timeslot beingprocessed of the sine wave signal which has been arbitrarily shiftprocessed. As a result, the sample value of the output sine wave signalsample is combined with the low frequency signal as the sine wavecomponent configuring the high frequency component.

At a step S85, the generating unit 141 determines whether or not the endof one frame has been reached. For example, when the zone for the finaltimeslot configuring the frame is being processed, that is to say, whenall timeslots in the frame have been processed, this is determined thatthe end of the frame has been reached.

When it has been determined that the end of the frame has not beenreached at the step S85, the next timeslot is selected as that to beprocessed, the processing returns to step S84, and the previouslydescribed processing repeats. Conversely, when it has been determinedthat the end of the frame has been reached at the step S85, the sinewave signal generation processing terminates, and afterwards, theprocessing proceeds to the step S59 in FIG. 6.

In this way, the sine wave information decoding unit 105 shifts theemergence start position of the sine wave signal to the combinationstart position on the basis of the sine wave information, and outputsthe shifted sine wave signal. As a result, the combination of the sinewave is started at a more accurate position in one frame, and so audioat a higher audio quality may be obtained.

Second Embodiment [Configuration Example of Encoding Device]

Though it has been described above that the combination start positionrepresenting the time (number of samples) from the beginning position ofthe frame until the position at which the combination of the sine wavesignal should start is included in the sine wave information,information of the difference between the combination start position andthe noise boundary position may be included.

In this case, the encoding device is configured as illustrated in FIG.8. Further, the components in FIG. 8 that correspond to those in FIG. 1have the same reference numerals, and so their descriptions will beomitted as appropriate. An encoding device 171 in FIG. 8 and theencoding device 11 are different in that a difference calculating unit181 is newly provisioned in the sine wave information generating unit 26of the encoding device 171, and so are the same regarding othercomponents.

The difference calculating unit 181 in the sine wave informationgenerating unit 26 calculates the difference between the combinationstart position of the sine wave signal detected by the positiondetection unit 62 and the noise boundary position. The sine waveinformation generating unit 26 supplies information made up from thedifference information representing the difference with the noiseboundary position calculated by the difference calculating unit 181 andthe information representing whether or not the sine wave signal hasbeen detected to the encoding stream generating unit 27 as the sine waveinformation.

[Description of Encoding Processing]

Next, the encoding processing performed by the encoding device 171 willbe described with reference to the flowchart in FIG. 9. Further, theprocessing of the step S111 through the step S118 are the same as thestep S11 through the step S18 in FIG. 2, and so their description isomitted.

At a step S119, the boundary calculating unit 52 in the noise envelopeinformation generating unit 25 detects the noise boundary position foreach band at the high frequency side. Then, at a step S20, the noiseenvelope information generating unit 25 generates the noise envelopeinformation for each band at the high frequency side, and supplies thisto the encoding stream generating unit 27. Further, at the step S119 andstep S120, the same processing as at step S20 and step S21 in FIG. 2 isperformed.

At a step S121, the difference calculating unit 181 in the sine waveinformation generating unit 26 calculates the difference between thenoise boundary position and the combination start position of the sinewave signal detected by the position detection unit 62.

For example, as illustrated in FIG. 10, the time (number of samples)from the start position of the sine wave combination until the noiseboundary position is calculated as the difference. Further, thehorizontal axis in the figure represents the timeline. Also, an arrowFS11 and an arrow FE11 in FIG. 10 represent the start position and theend position of the frame, respectively.

According to the example in FIG. 10, the position represented by anarrow N11 in the frame represents the noise boundary position. Also, thecombination start position of the sine wave signal is the positionrepresented by an arrow G11, and the combination start position ispositioned before the noise boundary position. Therefore, the sine wavesignal is combined in the zone from the combination start positionrepresented by the arrow G11 until the end position of the frame.

According to this example, the length of time (temporal distance) fromthe combination start position represented by the arrow G11 until thenoise boundary position represented by the arrow N11 is designated asthe difference information with the noise boundary position. Here, thetime from the combination start position until the noise boundaryposition is an integral multiple of the timeslot length.

By using the difference information representing the time from thecombination start position until the noise boundary position obtained inthis way, a more accurate combination start position may also beidentified at the decoding side of the audio signal, and so audio at ahigher audio quality may be obtained.

Returning to the description of the flowchart in FIG. 9, after thedifference information with the noise boundary position is obtained atthe step S121, the processing proceeds to a step S122.

At a step S122, the sine wave information generating unit 26 generatesthe sine wave information for each band at the high frequency side, andsupplies this to the encoding stream generating unit 27.

For example, the sine wave information generating unit 26 designates theinformation made up from the information representing whether or not thesine wave has been detected from the high frequency band and thedifference information between the combination start position and thenoise boundary position as the sine wave information. At this time, theencoding unit 63 in the sine wave information generating unit 26performs the variable length encoding of the difference information withthe noise boundary position. The sine wave information generating unit26 supplies the sine wave information made up from the differenceinformation processed by the variable length encoding and theinformation representing whether or not the sine wave signal has beendetected to the encoding stream generating unit 27.

After the sine wave information is generated, the processing at a stepS123 is performed and the encoding processing terminates, and as theprocessing at the step S123 is the same as the processing at the stepS22 in FIG. 2, so its description is omitted.

As previously described, the encoding device 171 generates and outputsthe encoding stream made up from the low frequency signal, the envelopeinformation, the noise envelope information, and the sine waveinformation. At this time, by detecting a more accurate combinationstart position of the sine wave signal and generating sine waveinformation including the difference information used for identifyingthis combination start position, a more accurate combination of the sinewave signal may be performed during decoding, and so audio at a higheraudio quality may be obtained as a result.

[Configuration Example of Decoding Device]

Also, a decoding device that receives the encoding stream transmittedfrom the encoding device 171, and obtains the audio signal from theencoding stream is configured as illustrated in FIG. 11. Further, thecomponents in FIG. 11 that correspond to those in FIG. 5 have the samereference numerals, and so their descriptions will be omitted asappropriate. A decoding device 211 in FIG. 11 and the decoding device 91are different in that a position calculating unit 221 is newlyprovisioned in the sine wave information decoding unit 105 of thedecoding device 211, and so are the same regarding other components.

The position calculating unit 221 in the decoding device 211 calculatesthe combination start position of the sine wave signal from thedifference information obtained from the sine wave information and thenoise boundary position supplied from the noise envelope informationdecoding unit 104.

[Description of Decoding Processing]

Next, the decoding processing performed by the decoding device 211 willbe described with reference to the flowchart in FIG. 12. Note that, theprocessing from step S151 through step S157 is the same as theprocessing from step S51 through step S57 in FIG. 6, and so theirdescriptions are omitted. However, at the step S155, the noise envelopeinformation decoding unit 104 supplies the information representing thenoise boundary position included in the noise envelope informationobtained from the decoding to the sine wave information decoding unit105.

At a step S158, the sine wave information decoding unit 105 performs thesine wave signal generation processing, generates the sine wave signalfor each band at the high frequency side, and supplies this to the bandpass combination filter 106. Further, details of the sine wave signalgeneration processing will be described later.

After the sine wave signal generation processing has been performed, theprocessing at a step S159 is performed, and the decoding processingterminates, and as the processing at the step S159 is the same as thestep S59 in FIG. 6, its description will be omitted.

[Description of Sine Wave Signal Generation Processing]

Also, at the step S158 in FIG. 12, the sine wave information decodingunit 105 performs the sine wave signal generation processing illustratedin FIG. 13. Hereafter, the sine wave signal generation processingcorresponding to the processing at the step S158 will be described withreference to the flowchart in FIG. 13.

At a step S181, the position calculating unit 221 in the sine waveinformation decoding unit 105 calculates the combination start positionof the sine wave signal from the noise boundary position supplied fromthe noise envelope information decoding unit 104 and the differenceinformation obtained from the sine wave information. That is to say, thedifference in the time between the combination start position and thenoise boundary position is subtracted from the time from the startposition of the frame being processed until the noise boundary position,the time from the start position of the frame until the combinationstart position of the sine wave signal is obtained, and the timing(sample) of the combination start position is identified.

After the combination start position is calculated, the processing of astep S182 through a step S186 is performed, and the sine wave signalgeneration processing terminates, and as this processing is the same asthe processing of the step S81 through the step S85 in FIG. 7, theirdescriptions are omitted. After the sine wave signal generationprocessing terminates in this way, the processing proceeds to a stepS159 in FIG. 12.

In this way, the sine wave information decoding unit 105 calculates amore accurate combination start position of the sine wave signal fromthe difference information included in the sine wave information signaland the noise boundary position. As a result, the combination of thesine wave signal is started at a more accurate position in one frame,and so audio at a higher audio quality may be obtained.

Third Embodiment [Configuration Example of Encoding Device]

Though the second Embodiment has been described above with an example inwhich the difference information between the combination start positionand the noise boundary position is included in the sine waveinformation, information of the difference between the peak position ofthe combination start position and the high frequency signal envelopemay be included.

In this case, the encoding device is configured as illustrated in FIG.14. Further, the components in FIG. 14 that correspond to those in FIG.1 have the same reference numerals, and so their descriptions will beomitted as appropriate. An encoding device 251 in FIG. 14 and theencoding device 11 are different in that a peak detection unit 261 and adifference calculating unit 262 are newly provisioned in the sine waveinformation generating unit 26 of the encoding device 251, and so arethe same regarding other components.

According to the encoding device 251, the envelope information suppliedfrom the envelope information generating unit 24 to the noise envelopeinformation generating unit 25 is also supplied from the noise envelopeinformation generating unit 25 to the sine wave information generatingunit 26. The peak detection unit 261 detects the peak position of thehigh frequency signal envelope on the basis of the envelope informationsupplied from the noise envelope information generating unit 25.

The difference calculating unit 262 calculates the difference betweenthe combination start position of the sine wave signal detected by theposition detection unit 62 and the peak position of the high frequencysignal envelope. The sine wave information generating unit 26 suppliesthe information made up from the difference information representing thedifference with the peak position calculated by the differencecalculating unit 262 and the information representing whether or not thesine wave signal has been detected to the encoding stream generatingunit 27 as the sine wave information.

[Description of Encoding Processing]

Next, the encoding processing performed by the encoding device 251 willbe described with reference to the flowchart in FIG. 15. Further, theprocessing of the step S211 through the step S218 are the same as thestep S11 through the step S18 in FIG. 2, and so their description isomitted. However, at the step S214, the generated envelope informationis also supplied to the sine wave information generating unit 26 fromthe envelope information generating unit 24 through the noise envelopeinformation generating unit 25.

At a step S219, the peak detection unit 261 in the sine wave informationgenerating unit 26 detects the peak position of the high frequencysignal envelope on the basis of the envelope information supplied fromthe noise envelope information generating unit 25. For example, theposition where the gain of the high frequency signal enveloperepresented by the envelope information is at a maximum is detected asthe peak position of the high frequency signal envelope.

At a step S220, the difference calculating unit 262 calculates, for eachband at the high frequency side, the difference between the combinationstart position of the sine wave signal detected by the positiondetection unit 62 and the peak position of the envelope detected by thepeak detection unit 261.

For example, as illustrated in FIG. 16, the time (number of samples)from the start position of the sine wave combination until the peakposition is calculated as the difference. Further, the horizontal axisin the figure represents the timeline. Also, an arrow FS21 and an arrowFE21 in FIG. 16 represent the start position and the end position of theframe, respectively.

According to the example in FIG. 16, the envelope of the high frequencysignal is represented by a dotted line, and the position represented byan arrow P1 in the frame represents the peak position of this envelope.Also, the combination start position of the sine wave signal is theposition represented by an arrow G21, and the combination start positionis positioned before the peak position of the envelope. During thedecoding, the sine wave signal is combined in the zone from thecombination start position represented by the arrow G21 until the endposition of the frame.

According to this example, the length of time (temporal distance) fromthe combination start position represented by the arrow G21 until thepeak position of the high frequency signal envelope represented by thearrow P1 is designated as the difference with the peak position. Here,the time from the combination start position until the peak position isan integral multiple of the timeslot length.

By using the difference information representing the time from thecombination start position until the peak position obtained in this way,a more accurate combination start position may be identified duringdecoding of the audio signal, and so audio at a higher audio quality maybe obtained.

Returning to the description of the flowchart in FIG. 15, after thedifference information with the peak position is obtained at the stepS220, the processing proceeds to a step S221.

At the step S221, the sine wave information generating unit 26 generatesthe sine wave information for each band at the high frequency side, andsupplies this to the encoding stream generating unit 27.

For example, the sine wave information generating unit 26 designates theinformation made up from the information representing whether or not thesine wave has been detected from the high frequency band and thedifference information between the combination start position and thepeak position as the sine wave information. At this time, the encodingunit 63 in the sine wave information generating unit 26 performs thevariable length encoding of the difference information with the peakposition. The sine wave information generating unit 26 supplies the sinewave information made up from the difference information processed bythe variable length encoding and the information representing whether ornot the sine wave signal has been detected to the encoding streamgenerating unit 27.

After the sine wave information is generated, the processing at a stepS222 through a step S224 is performed and the encoding processingterminates, and as this processing is the same as the processing at thestep S20 through the step S22 in FIG. 2, so its description is omitted.

As previously described, the encoding device 251 generates and outputsthe encoding stream made up from the low frequency signal, the envelopeinformation, the noise envelope information, and the sine waveinformation. At this time, by detecting a more accurate combinationstart position of the sine wave signal and generating sine waveinformation including the difference information used for identifyingthis combination start position, a more accurate combination of the sinewave signal may be performed during decoding, and so audio at a higheraudio quality may be obtained as a result.

[Configuration Example of Decoding Device]

Also, a decoding device that receives the encoding stream transmittedfrom the encoding device 251, and obtains the audio signal from theencoding stream is configured as illustrated in FIG. 17. Further, thecomponents in FIG. 17 that correspond to those in FIG. 5 have the samereference numerals, and so their descriptions will be omitted asappropriate. A decoding device 301 in FIG. 17 and the decoding device 91are different in that a position calculating unit 311 is newlyprovisioned in the sine wave information decoding unit 105 of thedecoding device 301, and so are the same regarding other components.

The position calculating unit 311 in the decoding device 301 calculatesthe combination start position of the sine wave signal from thedifference information obtained from the sine wave information and theenvelope information supplied from the envelope information decodingunit 103.

[Description of Decoding Processing]

Next, the decoding processing performed by the decoding device 301 willbe described with reference to the flowchart in FIG. 18. Further, theprocessing of a step S251 through a step S257 are the same as the stepS51 through the step S57 in FIG. 6, and so their description is omitted.

At a step S258, the sine wave information decoding unit 105 performs thesine wave signal generation processing, generates the sine wave signalfor each band at the high frequency side, and supplies this to the bandpass combination filter 106. Further, details of the sine wave signalgeneration processing will be described later.

After the sine wave signal generation processing has been performed, theprocessing at a step S259 is performed, and the decoding processingterminates, and as the processing at the step S259 is the same as thestep S59 in FIG. 6, its description is omitted.

[Description of Sine Wave Signal Generation Processing]

Also, at the step S258 in FIG. 18, the sine wave information decodingunit 105 performs the sine wave signal generation processing illustratedin FIG. 19. Hereafter, the sine wave signal generation processingcorresponding to the processing at the step S258 will be described withreference to the flowchart in FIG. 19.

At a step S281, the position calculating unit 311 in the sine waveinformation decoding unit 105 calculates the combination start positionof the sine wave signal from the envelope information supplied from theenvelope information decoding unit 103 and the difference informationobtained from the sine wave information.

That is to say, the position where the gain of the high frequency signalenvelope represented in the envelope information is at a maximum iscalculated by the position calculating unit 311 as the peak position ofthe high frequency signal envelope. Then, the position calculating unit311 subtracts the difference in the time between the combination startposition and the peak position is subtracted from the time from thestart position of the frame being processed until the peak position, thetime from the start position of the frame until the combination startposition of the sine wave signal, and the timing (sample) of thecombination start position is identified.

After the combination start position is calculated, the processing of astep S282 through a step S286 is performed, and the sine wave signalgeneration processing terminates, and as this processing is the same asthe processing of the step S81 through the step S85 in FIG. 7, theirdescriptions are omitted. After the sine wave signal generationprocessing terminates in this way, the processing proceeds to a stepS259 in FIG. 18.

In this way, the sine wave information decoding unit 105 calculates amore accurate combination start position of the sine wave signal fromthe difference information included in the sine wave information and thepeak position of the high frequency signal envelope. As a result, thecombination of the sine wave signal is started at a more accurateposition in one frame, and so audio at a higher audio quality may beobtained.

Further, though an example has been described above in which thedetection of the peak position of the envelope is performed at thedecoding device 301 side, information representing the peak position maybe included in the sine wave information. In this case, the sine waveinformation generating unit 26 in the encoding device 251 generates thesine wave information including the information representing the peakposition, and the position calculating unit 311 in the decoding device301 calculates the combination start position from the differenceinformation and the information representing the peak position includedin the sine wave information.

Fourth Embodiment [Configuration Example of Encoding Device]

Though an example has been described above that the sine waveinformation included one type of previously determined information fromamong the combination start position, the difference information withthe noise boundary position, or the difference information with the peakposition, the information among these with the smallest encoding amountmay be selected to be included in the sine wave information.

In this case, the encoding device is configured as illustrated in FIG.20, for example. Further, the components in FIG. 20 that correspond tothose in FIG. 1 or FIG. 14 have the same reference numerals, and sotheir descriptions will be omitted as appropriate. An encoding device341 in FIG. 20 and the encoding device 11 in FIG. 1 are different inthat a peak detection unit 261, a difference calculating unit 351, and aselection unit 352 are newly provisioned in the sine wave informationgenerating unit 26 of the encoding device 341, and so are the sameregarding other components.

According to the encoding device 341, the envelope information suppliedfrom the envelope information generating unit 24 to the noise envelopeinformation generating unit 25 is also supplied from the noise envelopeinformation generating unit 25 to the sine wave information generatingunit 26, and the peak detection unit 261 detects the peak position ofthe high frequency signal envelope on the basis of the envelopeinformation.

The difference calculating unit 351 calculates the difference betweenthe combination start position of the sine wave signal detected by theposition detection unit 62 and the peak position of the high frequencysignal envelope. The difference calculating unit 351 also calculates thedifference between the combination start position and the noise boundaryposition.

The selection unit 352 selects the information that will result in thesmallest encoding amount after the variable length encoding from amongthe combination start position, the difference information with the peakposition, or the difference information with the noise boundaryposition. The sine wave information generating unit 26 supplies theinformation made up from the information representing the result of theselection by the selection unit 352, the information selected by theselection unit 352, and the information representing whether or not thesine wave signal has been detected, to the encoding stream generatingunit 27 as sine wave information.

[Description of Encoding Processing]

Next, the encoding processing performed by the encoding device 341 willbe described with reference to the flowchart in FIG. 21. Further, theprocessing of the step S311 through the step S321 are the same as thestep S111 through the step S121 in FIG. 9, and so their description isomitted.

However, at the step S321, the difference calculating unit 351 in thesine wave information generating unit 26 calculates the differencebetween the combination start position of the sine wave signal detectedby the position detection unit 62 and the noise boundary position foreach band at the high frequency side. Also, at the step S314, thegenerated envelope information is also supplied to the sine waveinformation generating unit 26 from the envelope information generatingunit 24 through the noise envelope information generating unit 25.

At a step S322, the peak detection unit 261 in the sine wave informationgenerating unit 26 detects, for each band at the high frequency side,the peak position of the high frequency signal envelop on the basis ofthe envelop information supplied from the noise envelope informationgenerating unit 25.

At a step S323, the difference calculation unit 351 calculates, for eachband at the high frequency side, the difference between the combinationstart position of the sine wave signal detected by the positiondetection unit 62 and the peak position of the envelope detected by thepeak detection unit 261.

Further, the same processing at the step S219 and the step S220 in FIG.15 is performed at the step S322 and the step S323.

At a step S324, the selection unit 352 selects, for each band at thehigh frequency side, the information that will result in the smallestencoding amount after the variable length encoding from among thecombination start position, the difference information between thecombination start position and the peak position, or the differenceinformation between the combination start position and the noiseboundary position. Then, the selection unit 352 generates the selectioninformation representing the result of this selection. At this time,only the encoding amount of the combination start position or similarmay be calculated and compared, or the actual combination start positionor similar information may be processed by the variable length encoding,and this encoding amount may be compared.

At the step S325, the sine wave information generating unit 26 generatesthe sine wave information for each band at the high frequency side, andsupplies this to the encoding stream generating unit 27.

Specifically, the sine wave information generating unit 26 designatesthe information made up from the information representing whether or notthe sine wave signal has been detected from the high frequency band, theselection information, and the information representing the selectioninformation as the sine wave information. At this time, the encodingunit 63 in the sine wave information generating unit 26 performs thevariable length encoding of the selection information and theinformation representing the selection information. The sine waveinformation generating unit 26 supplies the sine wave information madeup from the selection information and the information representing theselection information processed by the variable length encoding and theinformation representing whether or not the sine wave signal has beendetected to the encoding stream generating unit 27.

For example, when the information representing the selection informationis the difference information between the combination start position andthe peak position, the information made up from the selectioninformation, the difference information with the peak position, and theinformation representing whether or not the sine wave signal has beendetected is designated as the sine wave information. In this way, bygenerating the sine wave information including the information with thesmallest encoding amount that identifies the combination start positionof the sine wave signal, the encoding amount of the encoding stream maybe further reduced.

After the sine wave information is generated, the processing at a stepS326 is performed and the encoding processing terminates, and as thisprocessing is the same as the processing at the step S224 in FIG. 15,its description is omitted.

As previously described, the encoding device 341 generates and outputsthe encoding stream made up from the low frequency signal, the envelopeinformation, the noise envelope information, and the sine waveinformation. At this time, by generating the sine wave informationincluding the information with the smallest encoding amount from amongthe information that identifies the combination start position of thesine wave signal, the data amount of the encoding stream to betransferred may be reduced, and at the same time, a more accuratecombination of the sine wave signal may be performed during decoding atthe decoding side of the audio signal. As a result, audio at a higheraudio quality may be obtained.

[Configuration Example of Decoding Device]

Also, a decoding device that receives the encoding stream transmittedfrom the encoding device 341, and obtains the audio signal from theencoding stream is configured as illustrated in FIG. 22, for example.Further, the components in FIG. 22 that correspond to those in FIG. 5have the same reference numerals, and so their descriptions will beomitted as appropriate. A decoding device 381 in FIG. 22 and thedecoding device 91 are different in that a position calculating unit 391is newly provisioned in the sine wave information decoding unit 105 ofthe decoding device 381, and so are the same regarding other components.

The position calculating unit 391 in the decoding device 381 calculatesthe combination start position of the sine wave signal from either thedifference information with the peak position or the differenceinformation with the noise boundary position obtained from the sine waveinformation, depending on the selection information included in the sinewave information.

[Description of Decoding Processing]

Next, the decoding processing performed by the decoding device 381 willbe described with reference to the flowchart in FIG. 23. Further, theprocessing of a step S351 through a step S356 are the same as the stepS51 through the step S56 in FIG. 6, and so their description is omitted.

However, at the step 355, the noise envelope information decoding unit104 supplies the information representing the noise boundary positionincluded in the noise envelope information obtained by the decoding tothe sine wave information decoding unit 105.

At a step S357, the sine wave information decoding unit 105 decodes thesine wave information from the encoding stream decoding unit 101. Forexample, the selection information included in the sine waveinformation, and the information used to obtain the combination startposition identified by the selection information, are decoded.

At a step S358, the sine wave information decoding unit 105 performs thesine wave signal generation processing, generates the sine wave signalfor each band at the high frequency side, and supplies this to the bandpass combination filter 106. Further, details of the sine wave signalgeneration processing will be described later.

After the sine wave signal generation processing has been performed, theprocessing at a step S359 is performed, and the decoding processingterminates, and as the processing at the step S359 is the same as thestep S59 in FIG. 6, its description is omitted.

[Description of Sine Wave Signal Generation Processing]

Also, at the step S358 in FIG. 23, the sine wave information decodingunit 105 performs the sine wave signal generation processing illustratedin FIG. 24. Hereafter, the sine wave signal generation processingcorresponding to the processing at the step S358 will be described withreference to the flowchart in FIG. 24.

At a step S381, the position calculating unit 391 determines whether ornot the information used to obtain the combination start position of thesine wave signal represented by the selection information is theinformation actually representing the combination start position. Thatis to say, it is determined whether or not the combination startposition is included in the sine wave information.

In the event that determination is made in step S381 that theinformation represented by the selection information is the informationrepresenting the combination start position of the sine wave signal, theprocessing proceeds to a step S385.

Conversely, in the event that determination is made in step S381 thatthe information represented by the selection information is not be theinformation representing the combination start position of the sine wavesignal, the processing proceeds to a step S382.

At the step S382, the position calculating unit 391 determines whetheror not the information used to obtain the combination start position ofthe sine wave signal represented by the selection information is thedifference information between the combination start position and thenoise boundary position. That is to say, it is determined whether or notthe difference information with the noise boundary position is includedin the sine wave information.

When the information represented by the selection information isdetermined to be the difference information with the noise boundaryposition, the processing proceeds to a step S383.

At the step S383, the position calculating unit 391 in the sine waveinformation decoding unit 105 calculates the combination start positionof the sine wave signal from the noise boundary position supplied fromthe noise envelope information decoding unit 104 and the differenceinformation with the noise boundary position obtained from the sine waveinformation. After the combination start position is calculated, theprocessing proceeds to the step S385.

Also, when the information represented by the selection information isdetermined to not be the difference information with the noise boundaryposition in the step S382, that is to say, when the informationrepresented by the selection information is the difference informationbetween the combination start position and the peak position, theprocessing proceeds to a step S384.

At the step S384, the position calculating unit 391 in the sine waveinformation decoding unit 105 calculates the combination start positionof the sine wave signal form the envelope information supplied from theenvelope information decoding unit 103 and the difference informationwith the peak position of the high frequency signal envelope obtainedfrom the sine wave information.

That is to say, the position calculating unit 391 detects the positionwhere the gain in the high frequency signal envelope represented by theenvelope information is at a maximum as the peak position of the highfrequency signal envelope. Then, the position calculating unit 391subtracts the difference in time between the combination start positionand the peak position from the time from the start position of the frameto be processed until the peak position, obtains the time from the startposition of the frame until the combination start position of the sinewave signal, and identifies the timing (sample) of the combination startposition. After the combination start position is calculated, theprocessing proceeds to the step S385.

After the information represented by the selection information isdetermined to be the information representing the combination startposition at the step S381, or the combination start position iscalculated at the step S383, or the combination start position iscalculated at the step S384, the processing proceeds to the step S385.Then, the processing of the step S382 through a step S389 is performed,and the sine wave signal generation processing terminates, and as thisprocessing is the same as the processing of the step S81 through thestep S85 in FIG. 7, their descriptions are omitted. After the sine wavesignal generation processing terminates in this way, the processingproceeds to a step S359 in FIG. 23.

In this way, the sine wave information decoding unit 105 identifies theinformation included in the sine wave information from the selectioninformation, and arbitrarily calculates a more accurate combinationstart position of the sine wave signal according to the result of thisspecification. As a result, the combination of the sine wave signal isstarted at a more accurate position in one frame, and so audio at ahigher audio quality may be obtained.

The series of processing previously described may be executed byhardware, or may be executed by software. When the series of processingis executed by software, a program configuring this software may beinstalled into a computer built with specialized hardware, or byinstalling various programs from a program recording medium into ageneral purpose personal computer, for example, that may execute variousfunctions.

FIG. 25 is a block diagram illustrating a configuration example ofcomputer hardware for executing the previously described series ofprocessing as a program.

A CPU 501, ROM (Read Only Memory) 502, and RAM (Random Access Memory)503, are connected together in the computer by a bus 504.

Also, an input/output interface 505 is connected to the bus 504. Devicesconnected to the input/output interface 505 include an input unit 506made up of a keyboard, a mouse, a microphone, etc., an output unit 507made up of a display, speaker, etc., a recording unit 508 made up of ahard disk, non-volatile memory, etc., a communication unit 509 made upof a network interface, etc., and a drive 510 for driving a magneticdisk, an optical disk, a magneto-optical disk, or a removable media 511such as semiconductor memory.

According to the computer configured in this way, the CPU 501 loads andexecutes the program installed in the recording unit 508 into the RAM503 through the input/output interface 505 and bus 504, for example, toperform the previously described series of processing.

The program executed by the computer (CPU 501) may be recorded in theremovable media 511, which is a form of packaged media configured of,for example, a magnetic disk (including a floppy disk), an optical disk(such as CD-ROM (Compact Disc-Read Only Memory) or DVD (DigitalVersatile Disc)), a magneto-optical disk, or semiconductor memory, etc.,or may be supplied via a wired or wireless transmission medium such as alocal area network, the Internet, or a digital satellite broadcast.

Also, the program may be installed to the recording unit 508 through theinput/output interface 505 by installing the removable media 511 to thedrive 510. Also, the program may be installed to the recording unit 508after being received by the communication unit 509 via the wired orwireless transfer medium. Also, the program may be previously installedin the ROM 502 or the recording unit 508.

Further, the program executed by the computer may perform the processingin time-sequence order as described in the present specification, mayperform the processing in parallel, or at a necessary timing such aswhen a call is performed.

Further, the embodiments of the preset technology are not limited to thepreviously described embodiments, and various modifications may occurinsofar as they are within the scope of the present technology.

REFERENCE SIGNS LIST

-   -   11 encoding device    -   22 low frequency encoding unit    -   24 envelope information generating unit    -   25 noise envelope information generating unit    -   26 sine wave information generating unit    -   52 boundary calculating unit    -   61 sine wave detection unit    -   62 position detection unit    -   91 decoding device    -   102 low frequency decoding unit    -   103 envelope information decoding unit    -   104 noise envelope information decoding unit    -   105 sine wave information decoding unit    -   141 generating unit    -   181 difference calculating unit    -   221 position calculating unit    -   261 peak detection unit    -   262 difference calculating unit    -   311 position detecting unit    -   351 difference calculating unit    -   352 selection unit    -   391 position calculating unit

1. A signal processing device comprising: an extracting unit configured to extract an envelope information representing low frequency components of an audio signal and an envelope of high frequency components of the audio signal and a sine wave information used for identifying the frequency and emergence position of sine wave components included in the high frequency components; a pseudo high frequency generating unit configured to generate a pseudo high frequency signal configuring the high frequency components on the basis of the low frequency signal as the low frequency component and the envelope information; a sine wave generating unit configured to generate a sine wave signal at a frequency represented by the sine wave information and which designates the emergence position identified from the sine wave information as the start position; and a combining unit configured to combine the low frequency signal, the pseudo high frequency signal, and the sine wave signal to generate the audio signal.
 2. The signal processing device according to claim 1, wherein the sine wave information includes information representing the distance from the start position of a frame of the high frequency component until the emergence start position of the sine wave component as information used for identifying the emergence position.
 3. The signal processing device according to claim 1, further comprising: a noise generating unit configured to generate a noise signal configuring the high frequency components by adjusting the gain of each zone of a predetermined signal, in which the zones are divided by a noise boundary position represented by a noise envelope information, on the basis of information representing the gain of each zone represented by the noise envelope information; wherein the extracting unit further extracts the noise envelope information; and wherein the sine wave information includes information representing the distance from the noise boundary position until the emergence start position of the sine wave components as the information used for identifying the emergence position; and wherein the combining unit combines the low frequency signal, the pseudo high frequency signal, the sine wave signal, and the noise signal to generate the audio signal.
 4. The signal processing device according to claim 1, wherein the sine wave information includes information representing the distance from a peak position of the high frequency component envelope until the emergence start position of the sine wave component as the information used for identifying the emergence position.
 5. The signal processing device according to claim 1, wherein the sine wave information is extracted for each frame, and the sine wave generating unit generates the sine wave signal for the high frequency components of each frame.
 6. The signal processing device according to claim 1, wherein the sine wave information is extracted for each band configuring the high frequency components, and the sine wave generating unit generates the sine wave signal for each band.
 7. A signal processing method to control a signal processing device, the signal processing device including an extracting unit configured to extract an envelope information representing low frequency components of an audio signal and an envelope of high frequency components of the audio signal and a sine wave information used for identifying the frequency and emergence position of sine wave components included in the high frequency components, a pseudo high frequency generating unit configured to generate a pseudo high frequency signal configuring the high frequency components on the basis of the low frequency signal as the low frequency component and the envelope information, a sine wave generating unit configured to generate a sine wave signal at a frequency represented by the sine wave information and which designates the emergence position identified from the sine wave information as the start position, and a combining unit configured to combine the low frequency signal, the pseudo high frequency signal, and the sine wave signal to generate the audio signal, the method comprising the steps of: the extracting unit extracting the low frequency components, the envelope information, and the sine wave information; the pseudo high frequency generating unit generating the pseudo high frequency signal; the sine wave generating unit generating the sine wave information; and the combining unit combining the low frequency signal, the pseudo high frequency signal, and the sine wave signal to generate the audio signal.
 8. A program executing processing on a computer, the processing including the steps of envelope information representing low frequency components of an audio signal and an envelope of high frequency components of the audio signal and sine wave information used for identifying the frequency and emergence position of sine wave components included in the high frequency components are extracted, a pseudo high frequency signal configuring the high frequency components is generated on the basis of the low frequency signal as the low frequency component and the envelope information, a sine wave signal at a frequency represented by the sine wave information and which designates the emergence position identified from the sine wave information as the start position is generated, and the low frequency signal, the pseudo high frequency signal, and the sine wave information are combined to generate the audio signal.
 9. A signal processing device comprising: an envelope information generating unit configured to generate envelope information representing an envelope of a high frequency signal, which is the high frequency component of an audio signal; a sine wave information generating unit configured to detect a sine wave signal included in the high frequency signal, and generating a sine wave information used for identifying the frequency and emergence position of the sine wave signal; and an output unit configured to generate and outputting data made up from a low frequency signal, which is a low frequency component of the audio signal, the envelope information, and the sine wave information.
 10. The signal processing device according to claim 9, wherein the sine wave information includes information representing the distance from the start position of a frame of the high frequency component until the emergence start position of the sine wave signal as information used for identifying the emergence position.
 11. The signal processing device according to claim 9, further comprising: a noise envelope information generating unit configured to detect a noise signal included in the high frequency signal, and generating a noise envelope information made up from information representing a noise boundary position which divides the noise signal into a plurality of zones and information representing the gain of the noise signal in the zone; wherein the sine wave information includes information representing the distance from the noise boundary position until the emergence start position of the sine wave components as the information used for identifying the emergence position; and wherein the output unit generates and outputs data made up from the low frequency signal, the envelope information, the sine wave information, and the noise envelope information.
 12. The signal processing device according to claim 9, wherein the sine wave information includes information representing the distance from a peak position of the high frequency component envelope until the emergence start position of the sine wave component as the information used for identifying the emergence position.
 13. The signal processing device according to claim 9, wherein the sine wave information is generated for each frame.
 14. The signal processing device according to claim 9, wherein the sine wave information is generated for each band configuring the high frequency components.
 15. A signal processing method to control a signal processing device, the signal processing device including an envelope information generating unit configured to generate envelope information representing an envelope of a high frequency signal, which is the high frequency component of an audio signal; a sine wave information generating unit configured to detect sine wave information included in the high frequency signal, and generating a sine wave information used for identifying the frequency and emergence position of the sine wave signal; and an output unit configured to generate and output data made up from the low frequency signal, which is the low frequency component of the audio signal, the envelope information, and the sine wave information, the method comprising the steps of: the envelope information generating unit generating the envelope information; the sine wave information generating unit generating the sine wave information; and the output unit generating and outputting data made up from the low frequency signal, the envelope information, and the sine wave information.
 16. A program executing processing on a computer, the processing including the steps of generating envelope information representing an envelope of a high frequency signal, which is a high frequency component of an audio signal, detecting a sine wave signal included in the high frequency signal, and generating a sine wave information used for identifying the frequency and emergence position of the sine wave signal, and generating and outputting data made up from a low frequency signal, which is a low frequency component of the audio signal, the envelope information, and the sine wave information. 